<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>垂直布局</title>
    <style>
        header, main, footer {
            width: 1000px;
            margin: 0 auto;
        }
        header {
            height: 100px;
            background-color: silver;
        }
        main {
            height: 500px;
            background-color: #bfa;
            margin: 10px auto;
        }
        footer {
            height: 150px;
            background-color: tomato;
        }

    </style>
</head>
<body>
    <header>

    </header>

    <main>

    </main>

    <footer>

    </footer>
</body>
</html>